The Challenges of Transitioning Non-Browser Applications to SHA-2

Created on Mar 01 2016, 6:29 PM by Dean Coclin

Two weeks ago, Worldpay, a major international payment processor, approached Symantec and the CA/Browser Forum with an urgent situation.  A small but still meaningful portion of the payment terminals within their global network can only function using the SHA-1 hashing algorithm.

SHA-1 is an older technology that has been shown to be increasingly vulnerable.  According to the current CA/Browser forum standards, starting Jan 1, 2016 Certificate Authorities are no longer allowed to issue new public SHA-1 certificates (although existing certificates can remain in use until they expire or until browsers and operating systems block them, currently planned for January 1, 2017 by several browsers). 

While Worldpay made considerable efforts to identify all their servers and believed they had obtained all the required certificates last year, some were missed which service roughly 1% of their credit card terminals and ATM machines globally. Due to Worldpay’s large global footprint, that small percentage translates into a number of potentially impacted businesses and end consumers.   

Following Worldpay’s request to the CA/Browser Forum, Symantec followed up with each of the major browsers directly.  After a public discussion on the Mozilla Dev Security Policy list, Mozilla proposed an approach that would enable Worldpay to get the required exception while minimizing the risk associated with additional SHA-1 certificate issuances.

The long-standing concerns about continued use of SHA-1 were reiterated by many as were the practical issues posed by Worldpay. We took this issue very seriously, as we had to weigh the additional risk against the potential negative disruption to Worldpay’s global merchant network and consumers.  After ruling out other possible technical options, we concluded that the approach proposed by Mozilla was the best available option. We issued these exception certificates to Worldpay last week and we will continue to work with them on alternate solutions that will adhere to industry best practices for certificate security, compliance, and management. A key element in our decision to issue these exception certificates was that they will be used only with non-browser clients – allowing the browsers to proceed uninterrupted with their upcoming plans to disable SHA-1 support.

Recognizing today’s complex technical interdependencies, several in the CA/Browser Forum raised the question of how to avoid this type of issue in the future. We are working with Worldpay and other customers to deploy alternate solutions, such as Symantec’s Private CA offering, that will ultimately separate the handling of encryption in credit card terminals, ATMs, cable boxes, and other non-browser clients from that in popular web browsers.

Symantec fully understands and promotes the necessity for adherence to best practices for certificate security management. That said, we also understand that real-world implementation is sometimes more challenging than we might anticipate, and we need to work together to not only create the right incentives for 100% compliance, but also to handle these real-world cases with the right level of consideration and nuance. We believe by collaborating with Mozilla and others, we have found a short-term solution that will enable businesses around the globe to keep functioning while providing some additional time, clearly required, to allow for the technical migration to SHA-2.

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